Robert S Walker

Robert S Walker
University of Missouri | Mizzou · Department of Anthropology

PhD
Sciencing

About

91
Publications
50,784
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3,786
Citations
Additional affiliations
August 2009 - present
University of Missouri
Position
  • Professor (Associate)

Publications

Publications (91)
Article
Full-text available
European expansion and contact with indigenous populations led to catastrophic depopulation primarily through the introduction of novel infectious diseases to which native peoples had limited exposure and immunity. In the Amazon Basin such contacts continue to occur with more than 50 isolated indigenous societies likely to make further contacts wit...
Article
Full-text available
There are about 50 isolated indigenous societies across lowland South America, with limited to no contact with the outside world. Despite displacements , epidemics, and hostile interactions with outsiders, such tribes still manage to survive. How can we ensure the well-being of humanity's last known isolated peoples under such enormous and mounting...
Article
Full-text available
The headwaters of the Amazon Basin harbor most of the world's last indigenous peoples who have limited contact with encroaching colonists. Knowledge of the geographic distribution of these isolated groups is essential to assist with the development of immediate protec-tions for vulnerable indigenous settlements. We used remote sensing to document t...
Article
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Contemporary humans exhibit spectacular biological success derived from cumulative culture and cooperation. The origins of these traits may be related to our ancestral group structure. Because humans lived as foragers for 95% of our species' history, we analyzed co-residence patterns among 32 present-day foraging societies (total n = 5067 individua...
Article
Stone‐tipped weaponry was important to the survival of past peoples, and many functional and non‐functional factors likely influenced their design. Two functional factors that past peoples likely considered in the design of their stone tips are durability (whether a stone tip breaks or not) and robusticity (how much damage is incurred upon breakage...
Article
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Stone lanceolate projectile points are characterized as having a lance shape with a tip tapering to an apex and are found in the archaeological record at different times and places across the world. In North America, lanceolate points are an important component of the Paleoindian period. One of the main factors in the design of lanceolate points is...
Article
Experimental archaeology continues to mature methodologically and theoretically. Around the world, practitioners are increasingly using modern materials that would have been unavailable to prehistoric people in archaeological experiments. The use of a modern material substitute can offer several benefits to experimental method, design, control, rep...
Article
This study is an experimental assessment of Clovis knife use. This work is the third contribution in a series of experiments aimed at shedding light on the functional performance of distinct Clovis “point” forms. Here, we used seven replica Clovis point forms, representing the average and extremes of observed Clovis form, in two cutting tasks: rope...
Preprint
Full-text available
Estimating the total human population size (i.e., abundance) of the preagricultural planet is important for setting the baseline expectations for human-environment interactions if all energy and material requirements to support growth, maintenance, and well-being were foraged from local environments. However, demographic parameters and biogeographi...
Article
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Abstract Across the planet the biogeographic distribution of human cultural diversity tends to correlate positively with biodiversity. In this paper we focus on the biogeographic distribution of mammal species and human cultural diversity. We show that not only are these forms of diversity similarly distributed in space, but they both scale superli...
Article
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In Late Pleistocene North America colonizing hunter-gatherers knapped and used Clovis fluted projectile points. During their expansion the size and shape of Clovis points changed significantly. Archaeologists know that cultural drift contributed to this variation, but is it possible that this single source could alone generate so much variation so...
Chapter
Comparative phylogenetic analyses based on linguistic data are useful for reconstructing the cultural evolution of recent expansions of humans around the world. It is an exciting time for phylogenetic comparative studies in lowland South America given the emergence of more comprehensive ethnolinguistic datasets. Phylogenetic methods can now be appl...
Article
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Human societies exhibit a diversity of social organizations that vary widely in size, structure, and complexity. Today, human sociopolitical complexity ranges from stateless small-scale societies of a few hundred individuals to complex states of millions, most of this diversity evolving only over the last few hundred years. Understanding how sociop...
Preprint
The human species is diverse in the size, structure and complexity of our social organizations. Today, human sociopolitical complexity ranges from stateless small-scale societies to complex states that integrate millions of individuals over vast geographic areas. Here, we explore major transitions across this range of complexity. In particular, we...
Preprint
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Group living is common in mammals, particularly in primates and humans. Across species, groups are social networks where co-residing members exchange information and balance trade-offs between competition and cooperation for space, resources, and reproductive opportunities. From a macroecological perspective, species-specific group sizes are ultima...
Article
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The expansion of the human species out of Africa in the Pleistocene, and the subsequent development of agriculture in the Holocene, resulted in waves of linguistic diversification and replacement across the planet. Analogous to the growth of populations or the speciation of biological organisms, languages diversify over time to form phylogenies of...
Article
Full-text available
The expansion of the human species out of Africa in the Pleistocene, and the subsequent development of agriculture in the Holocene, resulted in waves of linguistic diversification and replacement across the planet. Analogous to the growth of populations or the speciation of biological organisms, languages diversify over time to form phylogenies of...
Preprint
Full-text available
The expansion of the human species out of Africa in the Pleistocene, and the subsequent development of agriculture in the Holocene resulted in waves of linguistic diversification and replacement across the planet. Analogous to the growth of populations or the speciation of biological organisms, languages diversify over time to form phylogenies of l...
Article
Full-text available
Background The world’s last uncontacted indigenous societies in Amazonia have only intermittent and often hostile interactions with the outside world. Knowledge of their locations is essential for urgent protection efforts, but their extreme isolation, small populations, and semi-nomadic lifestyles make this a challenging task. Methods Remote sens...
Preprint
Full-text available
Background. The world’s last uncontacted indigenous societies in Amazonia have only intermittent and often hostile interactions with the outside world. Knowledge of their locations is essential for urgent protection efforts, but their extreme isolation, small populations, and semi-nomadic lifestyles make this a challenging task. Methods. Remote sen...
Preprint
Full-text available
Background. The world’s last uncontacted indigenous societies in Amazonia have only intermittent and often hostile interactions with the outside world. Knowledge of their locations is essential for urgent protection efforts, but their extreme isolation, small populations, and semi-nomadic lifestyles make this a challenging task. Methods. Remote sen...
Article
Full-text available
Short-term hunter-gatherer residential camps have been a central feature of human settlement patterns and social structure for most of human evolutionary history. Recent analyses of ethnohistoric hunter-gatherer data show that across different environments, the average size of hunter-gatherer bands is remarkably constant and that bands are commonly...
Article
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Background: All biological populations exhibit fluctuations in size over time due to stochastic variation in growth rates that result in local extinctions, but these dynamics are poorly understood in traditional human populations. Here, we explore extinction processes over human evolutionary history due to the effects of (i) demographic stochastici...
Article
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Partible paternity, the belief that a child can have more than one biological father, is widespread in lowland South America. An analysis of demographic data sets from four lowland tribes (Aché, Barí, Ese Eja, and Surui) reveals a systematic variation in the sex ratios of live births with respect to the number of fathers to whom the births are attr...
Article
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In many primates, including humans, the vocalizations of males and females differ dramatically, with male vocalizations and vocal anatomy often seeming to exaggerate apparent body size. These traits may be favoured by sexual selection because low-frequency male vocalizations intimidate rivals and/or attract females, but this hypothesis has not been...
Article
Full-text available
At least 50 indigenous groups spread across lowland South America remain isolated and have only intermittent and mostly hostile interactions with the outside world. Except in emergency situations, the current policy of governments in Brazil, Colombia, and Peru towards isolated tribes is a “leave them alone” strategy, in which isolated groups are le...
Data
High-resolution imagery information. Here is the information for the recent high-resolution satellite imagery purchased from DigitalGlobe and used for heads-up digitization for each site (PAN = panchromatic, MS = multispectral). We compared the total cleared area with Global Forest Change areas using cumulative estimates over the previous 3 years w...
Article
Full-text available
Studies of cultural adaptation and evolution are important for advancing our knowledge of what it means to be human and helping to move us toward a richer explanation of human variation. Considerable progress has been made in understanding cultural evolution using linguistic phylogenies to track the evolution of inheritance, residence, kinship, mar...
Article
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Objectives: Genealogies contain information on the prevalence of different sibling types that result from past reproductive behavior. Full sibling sets stem from stable monogamy, paternal half siblings primarily indicate male reproductive skew, and maternal half siblings reflect unstable pair bonds. Methods: Full and half sibling types are calcu...
Chapter
Full-text available
This essay addresses the significance and evidence surrounding the debate about how hunter-gatherers and other humans organize their residential groups. In most species of mammals, either males or female remain in their natal group (the philopatric sex) while the other sex disperses at maturity (the dispersing sex). Sex-biased philopatry and disper...
Article
Full-text available
Partible paternity refers to the conception belief that children can have multiple fathers (" co-fathers ") and is common to indigenous cultures of lowland South America. The nature of social relationships observed between co-fathers reveals information about the reproductive strategies underlying partible paternity. Here we analyze clan, genealogi...
Article
Full-text available
Partible paternity refers to the conception belief that children can have multiple fathers (“co-fathers”) and is common to indigenous cultures of lowland South America. The nature of social relationships observed between co-fathers reveals information about the reproductive strategies underlying partible paternity. Here we analyze clan, genealogica...
Preprint
Full-text available
Partible paternity refers to the conception belief that children can have multiple fathers (“co-fathers”) and is common to indigenous cultures of lowland South America. The nature of social relationships observed between co-fathers reveals information about the reproductive strategies underlying partible paternity. Here we analyze clan, genealogica...
Preprint
Full-text available
Partible paternity refers to the conception belief that children can have multiple fathers (“co-fathers”) and is common to indigenous cultures of lowland South America. The nature of social relationships observed between co-fathers reveals information about the reproductive strategies underlying partible paternity. Here we analyze clan, genealogica...
Article
Full-text available
The vast forests on the border between Brazil and Peru harbour a number of indigenous groups that have limited contact with the outside world. Accurate estimates of population sizes and village areas are essential to begin assessing the immediate conservation needs of such isolated groups. In contrast to overflights and encounters on the ground, re...
Article
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Some cross-cultural evidence suggests lethal coalitionary aggression in humans is the product of residence and descent rules that promote fraternal interest groups, i.e., power groups of coresident males bonded by kinship. As such, human lethal coalitions are hypothesized to be homologous to chimpanzee (Pan troglodytes) border patrols. However, hum...
Article
Full-text available
Hypotheses on the benefits of the practice of partible paternity are tested using demographic data for Ache foragers of Paraguay. Partible paternity refers to the institution of multiple males considered to contribute to the conception of a single offspring. Analyses focus on patterns of primary and secondary co-fatherhood among men, genealogical r...
Article
Full-text available
The relatedness of human groups has important ramifications for kin (group) selection to favor more collective action and invites the potential for more exploitation by political leaders. Endogamous marriages among kin create intensive kinship systems with high group relatedness, while exogamous marriages among nonrelatives create extensive kinship...
Article
Full-text available
Fissions of human communities are monumental occasions with consequences for cultural and genetic variation and divergence through time by means of serial founder effects. An ethnographic review shows that most human group fissions are fueled primarily by internal political conflict and secondarily by resource scarcity. As found for other social an...
Article
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Objectives: Greater Amazonia harbors as many as 100 locations of isolated indigenous peoples. Few options are available to assess the demographic health of these populations given their limited contact with the outside world. Remote sensing offers one option. Methods: An isolated village in Brazil near the Peruvian border is visible with Google...
Article
Full-text available
Marriages among kin have the dual effect of both increasing average group relatedness as well as reducing the total number of kin by eliminating more genealogically and geographically distant individuals from kinship networks. Marriage decisions therefore face a tradeoff between density of kin, or formation of intensive kinship systems, and the div...
Article
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Social norms that regulate reproductive and marital decisions generate impressive cross-cultural variation in the prevalence of kin marriages. In some societies, marriages among kin are the norm and this inbreeding creates intensive kinship networks concentrated within communities. In others, especially forager societies, most marriages are between...
Article
Full-text available
Lowland South America has long been a battle-ground between European colonization and indigenous survival. Initial waves of European colonization brought disease epidemics, slavery, and violence that had catastrophic impacts on indigenous cultures. In this paper we focus on the demography of 238 surviving populations in Brazil. We use longitudinal...
Article
Full-text available
The current study assessed the heritability of personality in a traditional natural-fertility population, the Ache of eastern Paraguay. Self-reports (n = 110) and other-reports (n = 66) on the commonly used Big Five Personality Inventory (i.e., extraversion, agreeableness, conscientiousness, neuroticism, openness) were collected. Self-reports did n...
Data
Assortative Mating. Both of these relations remain significant after controlling for age. Also, after simultaneously removing the two couples in the sample for which both members were interviewed by the research assistant, both relations remained significant. (TIFF)
Data
Lowess Function of Reproductive Success by Age. This Lowess curve (tension = 2/3) is a more flexible way to account for nonlinear variation than including quadratic components in regression analyses; however, the interpretation of results below did not differ if quadratic components rather than the Lowess values were used as controls. (TIFF)
Article
Full-text available
Postmarital residence patterns in traditional human societies figure prominently in models of hominid social evolution with arguments for patrilocal human bands similar in structure to female-dispersal systems in other African apes. However, considerable flexibility in hunter-gatherer cultures has led to their characterization as primarily multiloc...
Article
Full-text available
Violence was likely often a strong selective pressure in many traditional lowland South American societies. A compilation of 11 anthropological studies reporting cause of death shows that violence led to about 30% of adult deaths, of which about 70% were males. Here violent deaths are further itemized at the level of ethnographically-reported death...
Article
Full-text available
Question: The language-farming dispersal hypothesis postulates that the current bio-geographic distribution of global ethnolinguistic diversity is due to prehistoric demic expansions of agricultural populations. Does human population size increase as diet is increasingly based on agriculture, and is this relation moderated by agricultural potential...
Data
This paper discusses phylogenetic reticulation using linguistic data from the Automated Similar-ity Judgment Program or ASJP (Holman et al., 2008; Wichmann et al., 2010a). It contributes methodologically to the examination of two measures of reticulation in distance-based phylo-genetic data, specifically the δ score of Holland et al. (2002) and the...
Article
Full-text available
Recent advances in automated assessment of basic vocabulary lists allow the construction of linguistic phylogenies useful for tracing dynamics of human population expansions, reconstructing ancestral cultures, and modeling transition rates of cultural traits over time. Here we investigate the Tupi expansion, a widely-dispersed language family in lo...
Data
Comparisons between expert classifications and ASJP trees for the Tupi-Guarani subgroup. (DOCX)
Data
On the internal classification of Tupi-Guarani. (DOCX)
Data
Tupi cultural traits with possible states (top table) and data codings (bottom table). (DOCX)
Chapter
Full-text available
IntroductionComparative Human Population EcologyComparative Human Life HistoryHuman Ecological and Evolutionary EnergeticsConclusions
Article
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Previous studies have examined tooth eruption as it relates intrinsically to body mass, brain mass, and other life history variables, and extrinsically to ecological factors (e.g., age at foraging independence, environmental risk aversion, and maternal investment). Different models have been explored wherein each of these variables impacts ontogeny...
Article
Full-text available
Phylogenetic inference based on language is a vital tool for tracing the dynamics of human population expansions. The timescale of agriculture-based expansions around the world provides an informative amount of linguistic change ideal for reconstructing phylogeographies. Here we investigate the expansion of Arawak, one of the most widely dispersed...
Article
Full-text available
Humans evolved to withstand harsh environments by adaptively decreasing their body size. Thus, adaptation to a hostile environment defers the infancy-childhood transition age (ICT), culminating in short stature. In natural-fertility human societies, this transition is associated with weaning from breastfeeding and the mother's new pregnancy. We the...
Article
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The age of puberty has fallen over the past 130 years in industrialized, western countries, and this fall is widely referred to as the secular trend for earlier puberty. The current study was undertaken to test two evolutionary theories: (a) the reproductive system maximizes the number of offspring in response to positive environmental cues in term...
Article
This paper discusses phylogenetic reticulation using linguistic data from the Automated Similar-ity Judgment Program or ASJP (Holman et al., 2008; Wichmann et al., 2010a). It contributes methodologically to the examination of two measures of reticulation in distance-based phylo-genetic data, specifically the δ score of Holland et al. (2002) and the...
Article
Full-text available
The universality of marriage in human societies around the world suggests a deep evolutionary history of institutionalized pair-bonding that stems back at least to early modern humans. However, marriage practices vary considerably from culture to culture, ranging from strict prescriptions and arranged marriages in some societies to mostly unregulat...